1. Field of Utilization in Industry
This invention relates to polyarylenethioether primary melt formed articles or structures obtained by melt extrusion and having transparency and little coloration, which means in this specification self-coloration or discoloration and does not mean coloration by adding some colorants, to processes for producing the same, and to secondary melt formed articles such as films, sheets, and fibers obtained by melt processing of the primary articles in the form of pellets.
2. Prior Art
Polyarylenethioethers are thermoplastic resins having high crystallinity, which can be formed into products by injection molding, for example, as a matter of course, but also can be processed into other formed products such as films, sheets, plates, and fibers by extrusion, compression molding, inflation, melt spinning, and stretching, and they have been expected to provide melt processed articles having excellent properties.
However, most of the commercially available polyarylenethioethers in the prior art have been resins with apparent melt viscosities enhanced by "curing" of a relatively low melt viscosity polymer (namely, a low molecular weight polymer), that is, causing crosslinking, branching reactions, etc., to occur by a high temperature treatment of the polymer in the presence of oxygen, for example. The resins of melt viscosities increased by such "curing" have been accompanied by a number of problems such as excessive coloration, and insufficient mechanical strength due to many crosslinked branched structures.